If hydra-eval-jobs creates a new root, and hydra-update-gc-roots runs
before hydra-evaluator has had a chance to add the corresponding build
to the database, then hydra-update-gc-roots will remove the root. If
subsequently the Nix garbage collector kicks in, it may remove the
build's .drv file before the build is performed. Since evaluation of
the Nixpkgs and NixOS jobsets nowadays takes a lot of time (e.g. an
hour), the probability of this happening is fairly high.
The quick fix is not to delete roots that are less than a day old. So
long as evaluation doesn't take longer than a day, this should be fine
;-)
Fixes#166.
We now keep *all* unfinished evaluations of a jobset, in addition to
the <keepnr> most recent finished evaluations.
The main motivation is to ensure that mirror-{nixos,nixpkgs} work
properly: if building an evaluation takes too long, some of its builds
may already have been garbage-collected by the time the others finish.
We now keep all builds in the N most recent evaluations of a jobset,
rather than the N most recent builds of every job. Note that this
means that typically fewer builds will be kept (since jobs may be
unchanged across evaluations).
This gets rid of the openHydraDB function and ensures that we
open the database in a consistent way.
Also drop the PostgreSQL sequence hacks. They don't seem to be
necessary anymore.
Since it read the actual roots after determining the set of desired
roots, there was a possibility that it would delete roots added by
hydra-evaluator or hydra-build while hydra-update-gc-roots was
running. This could cause a derivation to be garbage-collected before
the build was performed, for instance. Now the actual roots are read
first, so any root added after that time is not deleted.
The hydra-update-gc-roots script is taking around 95 minutes on our
Hydra instance (though a lot of that is I/O wait). This patch
significantly reduces the number of database queries. In particular,
the N most recent successful builds for each job in a jobset are now
determined in a single query. Also, it removes the calls to
readlink().
The underscores are ugly and the .pl extension is an implementation
detail that shouldn't be visible to the outside.
Also, get rid of the *.in files. It's not really necessary to
generate them. And I was always modifying the wrong file.
2011-11-30 18:14:48 +01:00
Renamed from src/script/hydra_update_gc_roots.pl.in (Browse further)
